Antimicrobial Activity and Toxicity of Sophorolipids Produced by Candida haemulonis and Saccharomyces cerevisiae against Some Selected Microorganisms

Abstract

Sophorolipid have been identified to possess varying antagonism relationship to a number microbiota, although having been identified as being ecologically friendly. The biosafety of biologically synthesized materials has been identified as a major challenge to commercialization and scale-up. Sophorolipid was produced by Candida haemulonis and Saccharomyces cerevisiae in Palm oil mill effluent impacted soil in Emohua, Rivers State. Submerged fermentation was employed in the production of the sophorolipid while the Well-in-agar approach was employed in the antimicrobial susceptibility was conducted using 20%, 40%, 60%, 80% and 100% on both beneficial and pathogenic bacteria and fungi namely Staphylococcus sp, Nitrobacter sp, Klebsiella sp, Bacillus sp while the fungal flora were Aspergillus sp, Penicillium sp, Rhizopus sp, Candida sp, Mucor sp and Saccharomyces sp. Acute toxicity was conducted using Nitrobacter sp, Nitrosomonas sp and Thiobacillus sp. Probit based determination of acute toxicity after a 48hr and 96hr exposure to the test organisms. Antagonistic nature of the sophorolipids showed there was little or no antagonistic activity on the bacterial isolates than the fungal isolates. The sophorolipid formulation synthesized from both isolates were observed to have a zone of inhibition between 10 mm to 24 mm for Nitrosomonas sp. while to Aspergillus sp it had a range between 4.0 mm to 13.0 mm. Acute toxicity of sophorolipid produced by Candida haemulonis against Nitrosomonas sp 0.054 mg/L while to Thiobacillus sp it had an acute toxicity index of 0.107 mg/L.  This study identified that the sophorolipid produced by the yeast isolate had the potential of being employed in a number of sectors. This study has pioneered the untapped benefits in the POME-induced flora and how they can be veritable tools in the biotechnology industry.